Light-sensitive o-quinone diazide compositions and photographic reproduction processes and structures

ABSTRACT

A light-sensitive coating composition and a light-sensitive photomechanical structure, such as a printing plate or a photoresist is produced by coating a suitable planar substrate with a condensation product of an organic isocyanate and a polymeric resin having functional groups reactive with the isocyanate, such as a phenol-formaldehyde resin, and a light-sensitive diazo compound, such as the esters and amides of quinone diazides, the coating being softenable by exposure to light and subsequent treatment with a conventional liquid printing plate developer, such as an aqueous alkaline solution and/or an organic solvent.

This is a continuation, of application Ser. No. 572,662, filed Apr. 29,1975, now abandoned

BACKGROUND OF THE INVENTION

The present invention relates to light-sensitive compounds andcompositions suitable for use in the graphic arts. More particularly,the present invention relates to the use of the condensation products oforganic isocyanates and polymeric materials, carrying functional groupswhich are capable of reacting with the organic isocyanates, in themanufacture of printing plates and photoresists.

In the manufacture of positive-working printing plates and photoresists,derivatives diazides, as disclosed in U.S. Pat. Nos.3,046,110-3,046,119, 3,046,121-3,046,124, 3,106,465, 3,148,983,3,180,733, and 3,188,210, are widely used as light-sensitive materials.These naphthoquinone diazides are generally soluble in certain organicsolvents but are not soluble in water, weak acids and weak alkalies.Coating solutions can be prepared utilizing one or more of thesenaphthoquinone diazide light-sensitive compositions in organic solventsand the solution then coated on a suitable substrate such as aluminum,zinc, copper, plastics, paper, etc. The choice of the substrate dependson the intended use of the structure. When a substrate, coated with oneof these light-sensitive compositions, is exposed to light through animaged transparency, naphthoquinone diazides, in the exposed areas, arebelieved to be decomposed to the indene carboxylic acids, which aresoluble in a weak alkaline solution. Therefore, through the action ofthe light, a solubility differential between the exposed and unexposedareas results. The image can then be developed out by treatment with aproper weak alkaline developer solution and removal of the solubilizednon-image areas.

The compounds described in the above-mentioned U.S. patents, many ofwhich have been reported elsewhere, are low molecular weight esters andacid amides of quinone of naphthoquinone diazide. If such a compound isused individually, for instance, in the manufacture of lithographicprinting plates, it is deposited in crystalline form, which results inlowering the mechanical strength of the image obtained and making longpress runs difficult to attain. Accordingly, a suitable polymericresinous material is usually used as a carrier for the light-sensitivecompound to prevent it from cyrstallizing and to compensate for anyweakening of the mechanical strength. Suitable polymeric materials,which are employed for this purpose, are alkali-soluble resins such asshellac, styrene-maleic anhydride copolymers, hydrophobic thermoplasticpolyurethanes (U.S. Pat. No. 3,660,097) and, especially, low molecularweight condensation products of phenol and formaldehyde, the so-called`novolaks` (U.S. Pat. Nos. 3,148,983 and 3,188,210 and many others).However, when an alkali-soluble resin, such as the novolak availableunder the tradename of "Alnovol PN 430", manufactured by Chemische WerkAlbert, Wiesbaden-Biebrich, Germany, is used as recommended in the priorart, the unexposed areas of the sensitized coating do not possess therequisite adhesion to the substrate and tend to separate therefrom. Sucha tendency becomes particularly manifest during the developmentoperation, i.e., those instances wherein the plate is subjected tocontinued and prolonged immersion in the developer solution. Therefore,the image contrast and edge sharpness as well as press performancedeteriorate. In cases where good plate performance is required, it isnecessary to heat-treat the developed plates at an elevated temperatureso that a more durable printing surface can be obtained. However, suchtreatment usually yields a surface with many pinholes and spots.Therefore, the commercial value of such a system is greatly reduced.Conversely, when a hydrophobic polymeric material, such as the "Estane"thermoplastic polyurethanes sold by B. F. Goodrich Company, is used as acarrier (U.S. Pat. No. 3,660,097) for the light-sensitive compounds,considerable difficulty is encountered in removing the exposed area ofthe sensitized coating, since the aqueous developer solution isuniformly repelled from the surface. Therefore, a preponderance oflight-sensitive compounds would have to be incorporated in the coatingcompositions so that the sensitized layer will be more permeable to thealkaline developer. Use of a high percentage of sensitizer, in thismanner, yields coatings which require long exposure time and are slow todevelop, besides being unduly costly. In many instances, it is necessaryto add a small amount of organic solvents to the alkaline developer tospeed up the removal of the hydrophobic polymeric layer. In such cases,the resistance of the image areas to the alkaline developer is greatlyreduced.

In accordance with the present invention, these drawbacks of the priorart can be overcome, or at least considerably minimized, by usingpolymeric materials which have been especially chemically modified forphotographic reproduction applications.

One object of this invention is to provide such novelchemically-modified polymeric materials.

An additional object is to provide light-sensitive compositionscontaining isocyanate-modified polymeric materials.

A further object is to provide light-sensitive compositions, based onisocyanate-modified polymeric materials, and systems using thesecompositions to prepare lithographic printing plates, photoresists, andsimilar photomechanical images.

A still further object is to provide light-sensitive elements withimproved image adhesion and developer resistance.

Additional objects will be apparent to those skilled in the art from thefollowing detailed description of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, there is provided a novelclass of isocyanate-modified polymeric materials. The polymericmaterials of this invention can be obtained by conventional methods ofreacting organic isocyanates with suitable organic solvent-solublepolymers, bearing functional groups which are reactive toward theorganic isocyanates. The organic solvents chosen as the reaction mediumare inert toward and non-reactive with isocyanates, yet will readilydissolve the polymers to be modified. The polymeric materials obtainedafter such isocyanate modification, can be used, alone or in conjunctionwith other suitable polymeric materials, as carriers for light-sensitivequinone diazide compounds in a light-sensitive composition.

A detailed listing of the different functional groups which are reactivewith organic isocyanates can be found in Chemical Reviews, vol. 57, pp.47-76, 1957. Among the reactive groups mentioned, hydroxy, amino andthio groups are especially valuable, although other groups are not to beexcluded. These functional groups may be substituted directly on themain polymer chain as well as on side chains.

The organic solvent-soluble polymeric material, carrying reactivegroups, may be a natural polymer, a chemically-modified natural polymer,a synthetic polycondensation polymer or a polyaddition polymer, etc.,provided it is organic solvent-soluble. The following polymers are alsofound to be useful: hydroxy-containing acrylic resins, such ascopolymers containing hydroxyethyl methacrylate; polyesters ofpolyhydroxy intermediates, such as trimethylol propane, glycerol andsorbitol, which have hydroxyl groups remaining after incorporation inthe polymer chain; aminoaryl- and hydroxyarylaldehyde resins, such asaniline-formaldehyde resin and phenol-formaldehyde resin; and the like.

Any of a variety of organic isocyanates can be employed in preparing thepresent isocyanate-modified polymers, including aromatic, aliphatic andcycloaliphatic monoisocyanates, diisocyanates and polyisocyanates andcombinations thereof. Representative specific compounds, include; ethylisocyanate, 2-chloroethyl isocyanate, butyl isocyanate, t-butylisocyanate, hexyl isocyanate, octyl isocyanate, dodecyl isocyanate,phenyl isocyanate, o-, m-, p-chlorophenylisocyanates, o-, m-,p-methoxyphenyl-isocyanates, o-, m-, p-nitrophenyl isocyanates, o-, m-,p-tolyl isocyanates, cyclohexyl isocyanate, 1-naphthyl isocyanate,2,4-toluene diisocyanate, m-phenylene diisocyanate, 1,4-tetramethylenediisocyanate, 1,6-hexamethylene diisocyanate, 1,4-cyclohexylenediisocyanate, 1,5-tetrahydronaphthalene diisocyanate,trimethylhexamethylene diisocyanate, tris (4-isocyanatophenyl), theester of thionophosphoric acid, toluene diisocyanatetrimethylol propaneadduct, the reaction product of toluene diisocyanate and hexamethylenediisocyanate (3:2), and the like. The choice of the isocyanate to beutilized depends on the type of polymer to be modified, and the endresult to be expected, as is known to those skilled in the art.

The isocyanate-modified polymers of this invention can be prepared byreacting the hydroxyl, amino or thio groups on the polymers with theorganic isocyanates. The reaction is typically carried out in an organicsolvent which is completely inert toward the organic isocyanates, suchas tetrahydrofuran, dioxane, acetone, methyl ethyl ketone, and like, atroom temperature, or at reflux temperature. Usual catalysts for theisocyanate reaction, such as dibutyltin dilaurate, are optionally added.

A suitable method for preparing a lithographic printing plate is todissolve the isocyanate-modified polymers and the light-sensitivenaphthoquinone diazide derivatives in an organic solvent, such asacetone, methyl ethyl ketone, methyl cellosolve, methyl cellosolveacetate, tetrahydrofuran or mixtures thereof in various proportions, andto apply the solution onto a suitable base sheet or substrate,preferably an aluminum sheet. The coating may be applied, e.g. byimmersion or casting and draining, or by casting and centrifuging offthe excess of the solution, by brushing, by swabbing, by roller-coating,or by any other method known of application. The coating thus applied isthen dried at room temperature or at an elevated temperature.

The coating solution should contain at least about one part by weight ofeach of the light-sensitive compounds and the isocyanate-modifiedpolymeric materials per 100 parts of the organic solvent, desirablyabout 2 to about 20 parts, and preferably about 3 to about 10 parts. Theisocyanate-modified polymers can be used in an amount of up to about 10times by weight of the amount of the light-sensitive compounds.Desirably, the polymer is used in an amount of at least about 0.1 partby weight per part of the light-sensitive compound, and, preferably, inan amount of about 0.5 to about 5 parts by weight of polymeric materialper part of light-sensitive compound.

It is desirable to include in the coating a small amount of indicator toshow the image area on the developed plate, for example, a dye thatchanges color upon light exposure or upon decomposition of thenaphthoquinone diazide compounds, such as diethylaminoazobenzene, thusmaking it easy to distinguish the image area from the non-image areaimmediately upon exposure of the plate.

Significantly improved lithographic printing plates can be obtained bymodifying a phenol-formaldehyde resin, such as the "Alnovol PN 430"widely used in prior art, with organic isocyanates. The amount of theisocyanates is desirably in the range of 0.1 part to 60 parts by weightper 100 parts by weight of the resin, if a monoisocyanate is used; andfrom 0.1 part to 15 parts by weight per 100 parts by weight of theresin, if a diisocyanate or polyisocyanate is used. The preferred rangeis from about 2 to 35 parts by weight of monoisocyanate per 100 parts byweight of the resin, and from 0.1 part to 10 parts by weight ofdiisocyanate or polyisocyanate per 100 parts by weight of the resin. Thecondensation product formed by reaction of phenol-formaldehyde resinwith organic isocyanate are characterized by having free hydroxy groups.Lithographic printing plates, prepared with these isocyanate-modifiedphenol-formaldehyde resins in the coating formulations, showsubstantially increased press runs, significantly improved adhesion,wear and abrasion resistance and greater resistance to prolongedimmersion in an alkaline-aqueous developer than the correspondingprinting plates with unmodified resin in the formulation, and yet arestill easy to develop. Also, in those cases where the developed platesare subjected to heat treatment at an elevated temperature sufficient tocause melting of the coating, it is observed that the number of pinholesand spots is greatly reduced, or completely eliminated.

The compositions of the diazo sensitizers and organic isocyanates usedin the appended examples are given in the following Tables I and II,respectively. Table III gives specifications of the novolak resins usedin the examples.

TABLE I Diazo Sensitizers

Diazo I --2,2'Bis[naphthoquinone-(1,2)-diazide-(2)-sulfonyl-hydroxy-(5)]-dinaphthyl-(1,1')-methane

Diazo II -- 2,4-Bis-[naphthoquinone-(1,2)diazide-(2)-sulfonylhydroxy-(5)]-dihydroxybenzophenone

Diazo III -- Ester of naphthoquinone-(1,2)-diazide-(2)-sulfonic acid-(5)and 1,2,3-trihydroxybenzophenone

Diazo IV -- Naphthoquinone (1,2)-diazide-(2) sulfonic-acid chloride (4)

Diazo V --Naphthoquinone-(1,2)-diazide-(2)-sulfonylhydroxy-(4)-phenylcumene

TABLE II Isocyanates

1. Trimethyl hexamethylene diisocyanate

2. Toluene diisocyanate trimethylol propane adduct

3. Reaction product of toluene diisocyanate and hexamethylenediisocyanate (3:2)

4. Tris (4-isocyanatophenyl) ester of thionophosphoric acid

5. Butyl isocyanate

6. Tonco 70 (%) (Octadecylisocyanate-Technical--Upjohn Co.)

7. Tonco 90 (%) (Octadecylisocyanate-Technical--Upjohn Co.)

8. Cyclohexylisocyanate

9. P-methoxyphenylisocyanate

10. Hexamethylene diisocyanate

                  TABLE III                                                       ______________________________________                                        Alnovol Novolak Phenolic Resins                                               Alnovol No. Melting Point                                                                             Acid No.  Density                                     ______________________________________                                        PN 320      83°-88° C.                                                                  1         ca. 1.25                                    PN 430      110°-120° C.                                                                1           1.2                                       ______________________________________                                    

The following examples illustrate preferred embodiments of the inventionand are not to be considered as limiting the scope of the presentinvention. Unless otherwise stated, percentages and parts are all byweight.

EXAMPLE 1

An electrolytically-roughened aluminum foil is coated, for example on awhirler, with a solution containing 6.5 parts of butylisocyanate-modified phenolic resin and 2.2 parts of Diazo III in 100parts of methyl cellosolve. The coated aluminum foil is then dried,exposed to light under a positive master, developed with a 3.5 percentsolution of trisodium phosphate adjusted to pH 12.8 with sodiumhydroxide, rinsed with water and subsequently made ready for printing bywiping with a 1 percent solution of phosphoric acid. Prolonged immersionof the plate in the developer solution for 15 minutes caused practicallyno loss of the image. The plate was then run on a press, and showed nowear up to 65,000 impressions.

A butyl isocyanate-modified phenolic resin is prepared as follows:

100 parts of finely pulverized novolak (e.g. the product marketed underthe trademark "Alnovol PN 430") is dissolved in 200 parts oftetrahydrofuran. 7.5 parts of butyl isocyanate and 0.5 part ofdibutyltin dilaurate are added. The mixture is refluxed for 2 hours,then vacuum distilled. The residue is cooled down to room temperature,finally pulverized and then dried in a vacuum oven. The polymer melttemperature is 105° C. The infra-red spectrum showed no isocyanateabsorption at 2260 cm⁻¹.

EXAMPLE 2

The procedure of Example 1 was followed to prepare a lithographic platewith a coating containing the following ingredients.

    ______________________________________                                                                 Parts                                                ______________________________________                                        Diazo III                  2.2                                                "Tonco 70"-phenolic resin condensation product                                                           6.5                                                Methyl cellosolve          100.0                                              5-(p-Diethylamino-benzylidene) rhodamine                                                                 0.2                                                ______________________________________                                    

The plate was satisfactorily exposed and developed as described inExample 1, and had a useful life of over 45,000 impressions.

A "Tonco 70"-modified phenolic resin is prepared as follows:

100 parts of finely pulverized novolak ("Alnovol PN 430") is dissolvedin 200 parts of tetrahydrofuran. 7.5 parts of Tonco 70 (technical gradeoctadecyl-isocyanate marketed by the Upjohn Company, Polymer ChemicalsDiv., Laporte, Texas, U.S.A.) and 0.5 parts of dibutyltindilaurate areadded. The mixture is refluxed for 2 hours, 400 parts of methanol isthan added and the mixture is added dropwise to 3 liters of water. Theprecipitate is collected by filtration, and then dried in a vacuum oven.The polymer melt temperature is 98° C.

EXAMPLE 3

The procedure of Example 1 was followed to prepare a lithographic platewith a coating containing the following ingredients:

    ______________________________________                                                                 Parts                                                ______________________________________                                        Diazo III                  2.2                                                Cyclohexyl isocyanate-modified phenolic                                       resin                      6.5                                                Methyl Cellosolve          100.0                                              4-diethylaminoazobenzene   0.3                                                ______________________________________                                    

The plate was satisfactorily exposed and developed as described inExample 1, and had a useful press life of over 45,000 impressions.

A cyclohexyl isocyanate-modified phenolic resin is prepared according tothe general procedure described in Example 2.

EXAMPLE 4

The procedure of Example 1 was followed to prepare a lithographic platewith a coating containing the following ingredients.

    ______________________________________                                                                 Parts                                                ______________________________________                                        Diazo III                  2.2                                                P-methoxyphenyl isocyanate-modified phenolic                                  resin                      6.5                                                Methyl cellosolve          100.0                                              4-Diethylaminoazobenzene   0.3                                                ______________________________________                                    

The plate was satisfactorily exposed and developed as described inExample 1, and had a useful press life of over 55,000 impressions.

A p-methoxyphenyl isocyanate-modified phenolic resin is preparedaccording to the general procedure described in Example 2.

EXAMPLE 5

The procedure of Example 1 was followed to prepare a lithographic platewith a coating containing the following ingredients.

    ______________________________________                                                                   Parts                                              ______________________________________                                        Diazo III                    2.2                                              Hexamethylene diisocyanate-modified phenolic resin                                                         6.5                                              Methyl cellosolve            100.0                                            4-Diethylaminoazobenzene     0.3                                              ______________________________________                                    

The plate is exposed to light under a positive master, developed with a2 percent solution of trisodium phosphate, rinsed with water andsubsequently made ready for printing by wiping with 1 percent solutionof phosphoric acid. The developed plate is then exposed briefly to lightand then heated to 250° C. in an oven for 10 minutes. The printingsurface is found to be free of pinholes and spots.

A hexamethylene diisocyanate-modified phenolic resin is prepared asfollows:

100 parts of finely pulverized novolak ("Alnovol PN 430") is dissolvedin 200 parts of tetrahydrofuran and 4 parts of hexamethylenediisocyanate and 0.5 part of dibutyltin dilaurate are added. The mixtureis agitated at room temperature until it is completely in solution. Itis then set overnight. 200 parts of methyl alcohol is added to themixture. The solution is then added dropwise to 5 liters of water. Theprecipitate is collected by filtration and then dried in an oven. Thepolymer melt temperature is 110°-145° C.

In the following examples, diazo sensitizers, isocyanates, and novolaksare selected from Tables I-III, respectively. In addition, novolaks arereacted with isocyanates to form isocyanate-modified resins according tothe formulas enumerated in Table IV. The general procedure for thepreparation of resins 1-9 in Table IV, follows.

EXAMPLE 6

In a 3-necked flask, equipped with a stirrer, reflux condenser anddrying tube, tetrahydrofuran is introduced and then the appropriatenovolak resin added in one or two portions. The isocyanate and fourdrops of cobalt naphthenate are added with concurrent heating to 60° C.The reaction time is three hours at 60° C. Next, the solution is cooledto room temperature with continued stirring and stored until used.

                  TABLE IV                                                        ______________________________________                                         Isocyanate Modified Novolak Resins                                           The resins are the products of the reaction of                                the ingredients shown. (All weights are in grams)                             ______________________________________                                        1.      Alnovol PN 430        144.18                                                  Butyl isocyanate      4.96                                                    Toluene diisocyanate-                                                         trimethylolpropane adduct                                                                           1.86                                            2.      Alnovol PN 430        96.2                                                    Diphenylmethan-4,4'-                                                          diisocyanate          2.5                                             3.      Alnovol PN 320        173.0                                                   Reaction product of toluene                                                   diisocyanate and hexamethylene                                                diisocyanate (3:2)    17.4                                            4.      Alnovol PN 430        140.0                                                   Toluene diisocyanate-                                                         trimethylolpropane adduct                                                                           6.56                                            5.      Alnovol PN 430        233.0                                                   Trimethyl hexamethylene                                                       diisocyanate          5.25                                            6.      Alnovol PN 430        187.0                                                   Reaction product of toluene                                                   diisocyanate and hexamethy-                                                   lene diisocyanate (3:2)                                                                             8.59                                            7.      Alnovol PN 430        144.0                                                   Tris (4-isocyanatophenyl)                                                     ester of thionophosphoric                                                     acid                  4.65                                            8.      Alnovol PN 430        144.18                                                  Butyl isocyanate      4.96                                            9.      Alnovol PN 430        187.0                                                   Toluene diisocyanate-                                                         trimethylolpropane adduct                                                                           6.56                                            ______________________________________                                    

EXAMPLE 7

Wire brushed aluminum was coated with a light-sensitive solution of thefollowing composition:

    ______________________________________                                        0.5 g          Diazo I                                                        1.5 g          Diazo II                                                       6.0 g          Resin 1                                                        0.07 g         Dimethylaminoazobenzene                                        ______________________________________                                    

in a solvent mixture of 5 parts tetrahydrofuran, 4 parts ofmethylglycol, and 1 part of butyl acetate. A coating thickness of 2 g/m²was obtained.

EXAMPLE 8

Mechanically brushed aluminum was coated with a light-sensitive solutionof the following composition:

    ______________________________________                                        0.5 g          Diazo I                                                        1.5 g          Diazo II                                                       6.0 g          Resin 2                                                        0.1 g          Crystal violet                                                 0.07 g         Dimethylaminoazobenzene                                        ______________________________________                                    

in the same solvent mixture, resulting in the same coating thickness asin Example 1.

EXAMPLE 9

Wire brushed aluminum was coated with:

    ______________________________________                                        0.5 g          Diazo I                                                        1.5 g          Diazo II                                                       6.0 g          Resin 3                                                        0.1 g          Crystal violet                                                 0.07 g         Dimethylaminoazobenzene,                                       ______________________________________                                    

in a solvent mixture as in Example 7, to a coating thickness of 1.55g/m².

EXAMPLE 10

Wire brushed aluminum was coated with a solution of:

    ______________________________________                                        1.3 g          Diazo III                                                      0.7 g          Diazo I                                                        7.0 g          Resin 4                                                        0.1 g          Crystal violet                                                 0.06 g         Dimethylaminoazobenzene                                        ______________________________________                                    

as in Example 7.

EXAMPLE 11

Wet brushed aluminum was coated with a solution of the followingcomposition:

    ______________________________________                                        2.0 g        Diazo II                                                         0.5 g        Diazo IV                                                         8.0 g        Resin 5                                                          0.2 g        Epon 1001 (Shell Chemical Co.                                                 bisphenol A-epichlorohydrin reac-                                             tion product)                                                    0.08 g       Crystal violet,                                                  ______________________________________                                    

in the previous solvent mixture. A coating thickness of 2.3 g/m² wasobtained.

EXAMPLE 12

Electrochemically grained, anodized aluminum was coated with thefollowing composition:

    ______________________________________                                        1.3 g              Diazo V                                                    0.65 g             Diazo I                                                    7.8 g              Resin 6                                                    0.2 g              Epon 1001                                                  0.045 g            Crystal violet                                             0.09 g             Diazo IV.                                                  ______________________________________                                    

A coating thickness of 4.10 g/m² was obtained.

The coatings of Examples 7-12 were imaged as follows:

They were exposed under a positive transparent pattern so that step 4 ofthe UGRA stepwedge was just clean when the coating was developed with anaqueous alkaline developer of U.S. Pat. No. 3,110,596. After a rinsewith dilute phosphoric acid, the plate was mounted on an offset printingpress.

EXAMPLE 13

An aluminum/copper/chromium trimetal plate was coated with the followingcomposition:

    ______________________________________                                        2.5 g        Diazo III                                                        4.2 g        Resin 7                                                          0.84 g       Polyvinyl acetate, Hoechst AG                                    0.17 g       Crystal violet,                                                  ______________________________________                                    

from the usual solvent mixture, resulting in a coating thickness of 1.9g/m².

The coating was exposed through a negative transparent pattern anddeveloped with an aqueous alkali-soluble developer. The developed platewas etched with a mixture of sluminum and zinc chlorides containingphosphoric acid. The residual coating was removed with an alcoholicsolution of sulfuric acid.

EXAMPLE 14

A dimensionally-stable polyester film was coated with the solution ofthe following, in the same solvent mixtures used in Example 7:

    ______________________________________                                        0.81 g       Diazo III                                                        0.4 g        Resin 8                                                          0.4 g        Zapon Fast Red (made by BASF)                                    0.4 g        Zapon Fast Red BB                                                ______________________________________                                    

A coating thickness of 1 g/m² resulted. After exposure, the coating wasdeveloped with a diluted aqueous alkali solution of phosphates andmetasilicate salts.

EXAMPLE 15

A copper foil-phenolic resin laminate, conventionally used for printedcircuit manufacture, was coated with the following:

    ______________________________________                                        3.0 g             Diazo III                                                   10.0 g            Resin 9                                                     0.3 g             Castor oil                                                  0.5 g             Methylviolet BB,                                            ______________________________________                                    

in the usual solvent mixture. After the customary exposure anddevelopment with the solution of Example 14, the copperboard was etchedwith a concentrated ferric chloride solution.

EXAMPLE 16

A dimensionally-stable polyester film was coated with the following:

    ______________________________________                                        3.5 g     Diazo V                                                             12.0 g    Resin 10                                                            3.0 g     Copolymer of vinyl acetate and                                                crotonic acid                                                       5.0 g     Polyglycol (mol. wt. 2000)                                          4.5 g     Terpolymer of n-hexylmethacrylate,                                            methyl methacrylate, and methacrylic                                          acid                                                                0.05 g    Crystal violet                                                      12.0 g    Plexisol B-574 (low viscosity                                                 polyethylacrylate-40% solution                                                [made by Roehm AG Darmstadt])                                       ______________________________________                                    

A cover foil of polyethylene was placed in contact with the driedcoating. To make a printed circuit, the surface of a copper board wascleaned, the cover foil was stripped on and the coating surfacelaminated to the copper surface at about 120° C.; the polyester film wasremoved; and the transferred coating was post dried at 100° C., exposedand developed in an aqueous alkaline developer having a pH of 13.6. Thecoating is well suited as an etch resist for copper with strong ferricchloride solutions and as a plating resist.

It will be obvious to those skilled in the art that many modificationsmay be made within the scope of the present invention without departingfrom the spirit thereof, and the invention includes all suchmodifications.

What is claimed is:
 1. A positive-working, light-sensitive coatingcomposition comprising at least one solvent-soluble, isocyanate-free,free hydroxy-containing condensation product of an organic isocyanateand a phenol-formaldehyde novolak resin, in admixture with at least onelight-sensitive diazo compound selected from the group consisting ofesters and amides of o-quinone diazides and mixtures thereof, saidcomposition being soluble in aqueous alkaline developer solution afterexposure to light.
 2. A composition in accordance with claim 1 whereinthe printing plate developer is an aqueous alkaline solution.
 3. Acomposition in accordance with claim 1 wherein the printing platedeveloper is an organic solvent.
 4. A composition in accordance withclaim 1 wherein the developer solution is a mixture of an aqueousalkaline solution and an organic solvent.
 5. A composition in accordancewith claim 1 wherein the ratio of isocyanate to novolak resin is withinthe range of about 0.1 to 60 parts by weight of isocyanate per 100 partsby weight of novolak resin.
 6. A composition in accordance with claim 1wherein the organic isocyanate is selected from the group consisting ofa diisocyanate and polyisocyanate and is present in the range of about0.1 to 15 parts by weight per 100 parts by weight of novolak resin.
 7. Acomposition in accordance with claim 1 wherein said organic isocyanateis a mono-isocyanate.
 8. A composition in accordance with claim 7wherein the ratio of isocyanate to novolak resin is within the range ofabout 0.1 to 60 parts by weight of isocyanate per 100 parts by weight ofnovolak resin.
 9. A composition in accordance with claim 8 wherein theratio of mono-isocyanate to novolak resin is within the range of about 2to 35 parts by weight of mono-isocyanate per 100 parts by weight ofnovolak resin.
 10. A composition in accordance with claim 1 wherein saidcondensation product is present in the range of about 0.1 to 10 parts byweight per part by weight of said light-sensitive diazo compound.
 11. Alight-sensitive material comprising a supported positive-working,light-sensitive coating composition as described in claim
 1. 12. Alight-sensitive material in accordance with claim 11 in which theorganic isocyanate is a mono-isocyanate.
 13. A material in accordancewith claim 11 wherein the material is a printing plate.
 14. A materialin accordance with claim 9 wherein the support is an aluminum plate. 15.A material in accordance with claim 11 wherein the material is aphotoresist.
 16. A material in accordance with claim 11 wherein thesupport is an aluminum/copper/chromium trimetal plate.
 17. A material inaccordance with claim 11 wherein the support is a copper foil-phenolicresin laminate.
 18. A material in accordance with claim 11 wherein thesupport is a copper board.
 19. A method which comprises exposing asupported, light-sensitive coating composition as described in claim 1to light under a pattern and developing the resulting image with anaqueous alkaline solution and/or organic solvent which removes thelight-exposed areas of the coating.